"If legislation is passed to create an easier pathway for retaining foreign students that obtain advanced STEM degrees at U.S. universities, the impact could be large: about 96,200 incoming foreign students in 2010 could have become eligible for a green card upon graduation," writes Neil Ruiz, a senior policy analyst and associate fellow in Brookings' Metropolitan Policy Program. "Currently, only a fraction of these students attain a temporary skilled-worker visa after graduating. The H-1B visa program has been one of the main pathways for retaining American-trained foreign students."

Ruiz notes that the United States attracts 21 percent of all students who study abroad, a higher percentage than any other country. His definition of study abroad includes students in language and certification programs, K-12, associate, bachelor's, master's professional, and doctoral degree programs.

But since there are so many native students enrolled in U.S. higher education programs, foreign students make up only about 3.5 percent of higher education enrollment. That figure has remained relatively constant for the past 60 years. Most foreign students are now from Asia - about 64 percent - while slightly more than 8 percent are from Latin America.

Even though fewer foreigners study in other countries, they often make up a much larger share of students studying in those countries and some have an easier time staying after graduation. Of the eight countries studied where data is available, only China ranks below the U.S. in terms of the number of foreign students as a total percentage of higher education students.

Why does this matter?

Most foreign students currently come on F-1 visas, which are non-immigrant student visas that allow foreigners to enroll in academic or language training programs in the U.S. According to Brookings, smaller metro areas in the Midwest have the most incoming foreign students relative to their university student populations. If immigration reform allows these students to stay and work more easily after graduation, these metro areas could "experience the greatest impact in terms of access to a new labor pool."

Brookings also notes that in 2010, there were about 188,000 foreign students with F-1 visas enrolled in advanced degree programs. Of those, only about 26,500 transferred to an H-1B visa from F-1 status.

While some lawmakers have expressed concern that allowing students to stay will limit job opportunities for American students, the U.S. has been struggling to fill STEM jobs and there has been bipartisan agreement around the idea of allowing U.S.-educated foreigners with degrees in the STEM fields to stay and work.

"These students are considered particularly desirable because they, like their American counterparts, offer the types of skills critical to building a vibrant "knowledge" economy—whether in the United States or elsewhere," Ruiz writes, "Around the world, many nations have adjusted their immigration policies in recent years to better attract highly-educated foreigners."

We should know very soon whether the United States plans to move in that direction.